Riaz suffered an ankle injury in the defeat by India at Edgbaston on Sunday.
Pakistan Cricket Board (PCB) put in a request to the ICC technical committee and the 25-year-old's inclusion was accepted. Scans later revealed that he suffered a deltoid ligament complex after an eversion injury mechanism.
The left-arm paceman twisted his ankle in his follow-through while bowling his ninth over as Pakistan lost by a big margin to their Asian rivals.
Sri Lanka batman Chamara Kapugedera faces a nervous wait to discover if his Champions Trophy campaign is over after suffering an injury in practice yesterday.
It also meant he was unable to bat as Pakistan, chasing a revised target of 289 in 41 overs in a rain-affected match, slumped to 164 for nine after India had piled up 319 for three.
Pakistani cricketer Wahab Riaz took to Twitter to reach out to his fans and apologise for the performance he delivered in his side's opening game of Champions Trophy 2017 against India.
Pakistan now have to beat South Africa, the world s top-ranked ODI side, in their second Group B match at Edgbaston on Wednesday if they are to have any chance of qualifying for the semi-finals.